Mathematics Seminar 11/11/22

Abstract:  In ocean modeling, representing the effect of eddies and turbulent flows is important at all spatial scales. Even at high resolutions (~1km), there is always going to be unresolved eddies, and for this reason, adequate viscosity schemes in the momentum equation are required for the representation of unresolved subgrid eddy effects of dissipative nature. A popular choice in the ocean modeling community is the adoption of (bi)harmonic closures since they ensure model stability while parameterizing enstrophy cascade to grid-scale; however they are known to cause spurious dissipation of energy and so degrade the representation of nonlinear features, especially at low and medium resolutions. In this talk, we will present state-of-the-art energy dissipation minimizing closures that have been developed to mitigate such effects, together with a new ‘energy-neutral’ numerical closure developed at Los Alamos National Laboratory. The performance of our new approach - the Anticipated UpSTream (AUST) scheme-is examined using a range of idealized and realistic test cases within MPAS-Ocean, the ocean component of the E3SM earth system model. We show that our new AUST closure leads to significantly improved energetics, increasing the intensity and coherence of the circulation. Overall, the energy-conservative schemes presented are useful in better capturing the behavior of turbulent flows.

Biosketch: Dr. Calandrini received her PhD degree in Applied Mathematics from Texas Tech University in 2018. Before joining LANL, from 2018 - 2020 she was a postdoc at Florida State University, working with Prof. Max Gunzburger. Her research interests are in numerical methods for PDEs, fluid-structure interaction, time integration with applications in Earth system modeling (ocean modeling) and biomechanics.

For more information, please contact:  Dr. Vu Thai Luan (luan@math.msstate.edu) (662)-325-7162.